TESORO GOLDEN SABRE

[dfbowers]

I literally bought over a mile of .25mm wire off of ebay for 50 bucks! That should hold me for a lifetime.. I aim to make more coils!!

[simonbaker]

It's kind of tough in the house.. I have 4 computers running, two TVs, dimmer switches, and a few motors on things running.. I would say I get 30cm with a euro and 28cm with a 2008 quarter, with GB set correctly and disc set to just reject aluminum foil.. and that's with the standard 255 mm coil I would be curious to see what others observe as well.

That is excellent. I think you have the knack for making coils. I hope you keep making some more coils and PCBs and see if you get consistent results to help the rest of us understand what mistakes we're making.

Cheers,

-SB

[Dennis the Mennis]

Simon,

I just had another thought about the euro. If you look at one, it looks like a fat brass ring with stainless or something in the middle. possibly one of the better configurations for a target.. much like a gold ring. If you cut a ring, it goes almost dead as a target since you break the circuit that makes the back EMF. The same thing we do with our shielding. Even though a quarter is larger and possibly of higher conductivity, it's not that perfect "ring" shape. I guess when we are doing distance test on the table we should be comparing "oranges to oranges"??

Just a thought..
Don

http://en.wikipedia.org/wiki/Euro_coins

FYI


regards

Dennis the Mennis

[dfbowers]

It's kind of tough in the house.. I have 4 computers running, two TVs, dimmer switches, and a few motors on things running.. I would say I get 30cm with a euro and 28cm with a 2008 quarter, with GB set correctly and disc set to just reject aluminum foil.. and that's with the standard 255 mm coil I would be curious to see what others observe as well.

[simonbaker]

Simon,

I just had another thought about the euro. If you look at one, it looks like a fat brass ring with stainless or something in the middle. possibly one of the better configurations for a target.. much like a gold ring. If you cut a ring, it goes almost dead as a target since you break the circuit that makes the back EMF. The same thing we do with our shielding. Even though a quarter is larger and possibly of higher conductivity, it's not that perfect "ring" shape. I guess when we are doing distance test on the table we should be comparing "oranges to oranges"??

Just a thought..
Don

I agree. I figure it would be useful to test both so we have oranges and apples benchmarks depending on what you have handy. But the euro is the "gold" standard here, so got to get me one. Also, with quarters, you have to know whether you have an old silver one or a new copper-clad, further confusion. I would like to know what a really good TGSL air-tests with a modern quarter though.

-SB

[dfbowers]

Simon,

I just had another thought about the euro. If you look at one, it looks like a fat brass ring with stainless or something in the middle. possibly one of the better configurations for a target.. much like a gold ring. If you cut a ring, it goes almost dead as a target since you break the circuit that makes the back EMF. The same thing we do with our shielding. Even though a quarter is larger and possibly of higher conductivity, it's not that perfect "ring" shape. I guess when we are doing distance test on the table we should be comparing "oranges to oranges"??

Just a thought..
Don

[dfbowers]

Got my hands on a euro.. Forgot my son went to Sweden a few months back. A quarter does not respond like a euro.. The euro responds much better by a few cm. If you can get your hands on a brass arcade token, it's about the same.

Don

[simonbaker]

I agree that it would not be practical to run at 9V.. Just an observation that I made. It almost seems like the audio struggles a bit, and draws out the audio and makes it sound a little softer. Also, I wonder why I am running 5mA short on the current consumption (that is at steady state.. no signal). I will play around a bit to see if I can get you more details.

I don't have a euro, so I can't compare to some others. I do have a brass arcade token that looks to be similar sized and I can get around 30cm on that in open air. Mine seems to be hotter on low conductors, typical of higher frequency machines.

Don

I've been meaning to get a Euro also... I'd be interested in results for quarter.

I'm just surprised that the LM7808 works at all at 9v, but clearly it does, although maybe not regulating in normal way.

Your ICs are newer models and may draw less current.

I think its interesting what you found. I would go back and forth with 9v and 12v supplies and try to see what is different in waveforms. Maybe it shifts something into a better configuration that we should know about.

Keep us posted,

-SB

[dfbowers]

I agree that it would not be practical to run at 9V.. Just an observation that I made. It almost seems like the audio struggles a bit, and draws out the audio and makes it sound a little softer. Also, I wonder why I am running 5mA short on the current consumption (that is at steady state.. no signal). I will play around a bit to see if I can get you more details.

I don't have a euro, so I can't compare to some others. I do have a brass arcade token that looks to be similar sized and I can get around 30cm on that in open air. Mine seems to be hotter on low conductors, typical of higher frequency machines.

Don

[simonbaker]

Simon,

Yep, I'm using the LM7808. As you can see, it regulates down to 7.9V with a 12V source. The only difference in my circuit is that I am using one TL081 and one TL061 in place of the LM308s.. I need to order a pair of TL071s or TL081s I guess. I'm using cheap ceramic caps throughout except for polyester caps for the TX and RX tuning. No cable yet as I need to fill my coil shell. Otherwise, the circuit works exactly as advertised.

Oh, if you DO try to duplicate, try the AM mode as well.. on mine the performance gain is more pronounced there.

Thanks

DOn

Hi Don:

The LM7808 is supposed to need a 2 Volt headroom (dropout voltage) so normally it wouldn't be capable of regulating 8 volts output with 9 volts input. However, at lower currents, maybe you can squeeze a little less difference out.

It would be interesting to measure the voltage across the LM7808 to see what you're getting -- also the current (TGSL typically needs 30 to 40 mA).

Your result is interesting and worth investigating, even if a 9 volt battery is not a realistic use for this circuit (especially as it runs down). But it may be a clue to something.

By the way: what air depth do you get?

-SB

[dfbowers]

Here it is.. I just had it on another PC. I did use J107s for TR4 and TR5. Placement shows BF245Cs

[porkluvr]

Rev .3 final by SB 8/18/2009.. (was that your latest?) There was a post somewhere with details on how to make and wire the coil, PCB, schematic and parts placement all zipped. I think it was labeled "Correct and tested" or something like that .

Don

I'm sorry I wasn't more specific. I was mainly wondering if you employ a TX stabilizing FET or not.

I will try to find the zip file that you referenced.

Is there a stabilizing FET (or whatever it's called) in the your tx circuit? I was wondering because I seem to recall Ivconic as having abandoned that FET as inconsequential.

[dfbowers]

Rev .3 final by SB 8/18/2009.. (was that your latest?) There was a post somewhere with details on how to make and wire the coil, PCB, schematic and parts placement all zipped. I think it was labeled "Correct and tested" or something like that .

Don

[porkluvr]

... I replaced my 12V power source with an alkaline 9V battery and immediately noticed an increase in performance. I gained a significant (an inch or two) increase in depth, and the audio became slightly weaker, but longer and more drawn out. The thing that caught my attention was the increase in detection depth. Anyone have a 9V battery that they could drop in theirs to see if they experience the same?

Can you detail which variation of Ivconic's circuit you built? I mean, this thread is 165 pages long, and the circuit has gone through some upheaval.

I don't mean for you to post your schematic, but do you have a link to the page where it is?

(Throw me a bone!)

[dfbowers]

TGSL

Circuit close-up